In German Pat. No. 1,615,258 (equivalent to British Pat. No. 1,212,941), an overheating safety switch is inserted into the lower hot plate cover and has a ceramic housing, inside which are positioned a bimetallic strip and a snap switch. The safety switch is supported with its housing on the lower side of the hot plate. In addition to its connection to the mains supply, it has hot plate attachments for other hot plate connections, so that it simultaneously forms the passage for the connection through the hot plate cover. In German Gebrauchsmuster No. 6,803,971, the attachments are designed as openings in the housing.
German Offenlegungsschrift No. 2,735,426 (equivalent to U.S. Pat. No. 4,153,833) describes an overheating safety switch which simultaneously contains the connections, for example, screw connections of the hot plate and is attached externally onto the hot plate. A separate part is inserted into the cover for the lead-through passage of the hot plate connections. A curved bimetallic member projects through the lower cover into the chamber below the hot plate and transmits its working motion through a compression bar to the switch in the housing.
A comparable arrangement is known from German Pat. No. 2,620,004 (equivalent to British Pat. No. 1,577,367) and U.S. Pat. No. 4,122,330.
A safety switch is known from German Pat. No. 1,123,059 which consists of a small ceramic hollow body in which a snap switch is inserted and is influenced by a bimetallic strip. It is positioned in the unheated center of the hot plate. The bimetallic strip and the switch are positioned in the housing which is located on the lower side of the hot plate.